I am currently using PHOENICS 3.6.1 for the radiation simulation of a heated box.

Description of the simulation:

A 2m X 2m X 1m (high) box was constructed with 0.01m steel sheets (emissivity of 0.9) and insulated by 0.1m fibre glass slab. The box is placed in the centre of a larger ambient domain of about 12 m cubic. At the bottom of the 2m box, there is a 0.8m X 0.8m opening. The steel sheets inside the box are assumed to be maintained at a fixed temperature of 873k (600C). The box is inclined at 17 degree from the horizontal (achieved by applying X and Z direction gravity forces). Consequently, there are radiation losses as well as convection heat losses through the opening (which are the main interest of the study).

The observed problem:

The estimated radiation intensity through the box opening should be less than 33 kW/m2 (assuming the internal surfaces of the box are black body surfaces). However, the QRZ values at the opening of the box using Immersol appear to be several times higher than 33 kW/m2.

Your help in this problem is very appreciated. I can e-mail you the q1 file for reference.